Loop quantum cosmology (LQC) is a symmetry reduced application of loop quantum gravity (LQG), a theory that leads to a structure of space-time that is discrete at a very fundamental level. One main result of LQC is the resolution of cosmological and black hole singularities. LQC ultimately leads to models of the Universe that exhibit a “big-bounce” as opposed to a “big-bang”. This is understood as arising from the quantum nature of gravitation, which appears to be repulsive in the very early Universe. Here is a movie and snapshot, showing the dynamics of discrete quantum space using the basic principles of LQG: spinfoam, snapshot.

•Homogeneous Loop Quantum Cosmology (MB,GK,JP)

Homogeneous and isotropic cosmologies have been studied quite extensively in LQC. This project is about anisotropic models, i.e. Bianchi cosmologies and their solutions in the context of LQC. These models are relevant for an understanding of the very early Universe. One interesting thing that we have recently uncovered is that an evolution through such a singularity, provides perhaps an indication of different physics on the other side, which could be evidence of parameter change (see below). Here is a plot that indicates a different behavior in the wave-function of the Universe, it is passes through the classical singularity: plot.

•Black Holes in Loop Quantum Gravity (MB,GK,JP)

Loop quantum gravity also resolves the physical singularity that is present in the interior of black holes. Details associated to this work is likely to have impact on various significant aspects of black hole physics, including the issues associated to information loss and evaporation.

•Parameter change and Cosmological Natural Selection (GK)

Cosmological Natural Selection (CNS) is an idea that was proposed by Lee Smolin in his popular book, The Life of the Cosmos. The basic thesis of CNS is that the physical constants of Nature appear to be tuned to ensure that black holes arise and proliferate. Smolin speculates on a mechanism for change in the physical constants in a “big-bounce” scenario as we indicated above. This project is related to making further investigations into probing the validity of CNS.